LOS ANGELES , California -- Dr. Andre Berger sees himself as a pioneer . Where others in the medical community believe injections of human growth hormone should be given to adults in only rare cases , Berger believes it is a crucial part of keeping people young and vital .

Dr. Andre Berger says the patients requesting HGH from him are getting younger and younger .

Berger , who has been practicing anti-aging and holistic medicine for 30 years , says he is now prescribing injections of HGH to about one out of every four people he treats at his Rejuvalife Vitality Institute in Beverly Hills .

`` People come here for generally two reasons ; they want to look better , and they want to feel better , '' Berger says .

While Berger says most of his patients are middle-aged , he 's now getting calls from Hollywood 30-somethings wanting HGH and rap artists inquiring about illegal steroids , something he does not offer .

`` They feel that part of being a rap star is looking buff and having big muscles , etc. , so anything they can do to bring themselves to look like that is going to enhance the whole image , '' he says .

HGH has been used since the 1950s to help children with growth problems , but it stayed under the radar for other uses until 1990 , when Dr. Daniel Rudman reported in the New England Journal of Medicine that men taking a six-month course of HGH reduced their body fat by 14.4 percent while increasing lean muscle mass by 8.8 percent .

The study included just a dozen men , but it inspired a flood of anti-aging literature touting the benefits of growth hormone , along with countless Web sites selling HGH creams and sprays .

Endocrinologists say those products , though , are worthless -- the body can use HGH only when it 's injected to treat patients with HGH , Berger says they must be diagnosed with a deficiency of HGH , which happens naturally as the body ages .

`` It 's a very important hormone , but it 's not something to be taken in isolation , '' he says .

Berger says he prescribes HGH to restore normal levels of the hormone and makes it part of a broader long-term treatment program including diet , nutritional supplements , exercise and other hormone replacement .

Dennis Pelino , a 60-year-old Beverly Hills entrepreneur , says five years ago , he was having trouble keeping up with the younger people he was doing business with , so he started treatments , which included HGH injections .

`` My skin tone got a lot better . I just felt better , '' he says . `` My eyes got a lot brighter . My hearing , I swear , got better . ''

Pelino says HGH injections , along with a healthy diet , exercise , and supplements has made him feel 10 years younger .

`` I can keep up with people who are a lot younger than me , '' he says . `` I am not trying to set records , I am just trying to stay in the game , I am doing business here . ''

But critics argue that doctors are taking huge risks by administering HGH because it has n't been studied extensively long-term and says many of the same benefits can be found in diet and exercise alone .

`` There are serious side effects associated with using growth hormone for these individuals including an elevated risk of cancer , diabetes , '' says Dr. Jay Olshansky of the University of Illinois at Chicago .

Olshansky , who has studied anti-aging for over 20 years , contends that many of the claims are just false and says that only in the rarest of cases can HGH be prescribed legally .

`` It can be prescribed in adults for only two things ; muscle-wasting associated with HIV/AIDS , which is extremely rare , and for adult growth hormone deficiency , '' he says .

Still , celebrities including Sylvester Stallone and Suzanne Somers who have openly supported the use of HGH , have attracted those just seeking a new lease on life . Marketers for HGH therapies claim it 's become a $ 2 billion-a-year business , thanks in large part to aging baby boomers willing to pay big bucks to emulate the stars whose looks never seem to fade .

The Albany-Times Union recently reported , citing unnamed sources , that rapper 50 Cent and singer Mary J. Blige were among celebrity customers allegedly identified in a New York probe of doctors and pharmacists who illegally prescribe steroids or HGH .

The Times-Union report did not suggest there was evidence Blige or 50 cent took the drugs .

Blige denies taking any performance enhancing drugs , and 50 Cent has not commented . Neither star is accused of breaking the law . E-mail to a friend

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Doctor says more 30-somethings want steroids and HGH

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HGH first used to help children with growth problems

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Critics say there are health dangers